Drop lock bolt for gun



Jan- 13, 1959 R. G. NUTTING Em 2,868,082

DROP LOCK BOLT FOR GUN Filed Oct. 13, 1955 Zay INVENTOR. Rnherl E NuingfBYRDEETL mnargp Zbd Patented Jari. 13, 1959 DROP LDCK BOLT'FOR GUNRobert G. Nutting, Glenview, and Robert F. Windstrup, Chicago, Ill.,assignors, by mesne assignments, to the United States of America asrepresented by the Secretary of the Army Application October 13, 1955,Serial No. 540,362

3 Claims. (Cl. 89-190) Our invention pertains to a machine gun and moreparticularly to a gas-operated bolt therefor.

In the usual machine gun including a receiver, a feeder for conductingan ammunition belt therein and a bolt spring, a bolt operates inrearward kand forward strokes, from and to a battery position,responsive to discharge of cartridges in the barrel. The bolt includesenough mass and the rate of the spring is high enough to store kineticenergy from the discharge to operate the feeder, to strip livecartridges from the ammunition belt, to ram the cartridges from thefeeder into the barrel and to extract the cases of the cartridges fromthe barrel after the discharge. The rate of fire of the gun is inverselyproportionate to the mass of the bolt and the rate of the spring.

The machine gun of our invention is provided with a feeder for supplyingcartridges to a feed throat` to eliminate the feeding and strippingfunctions of the bolt and thereby reduce the kinetic energy required tobe stored by the bolt to increase the rate of the gun.

Itis an object of our invention to provide a gas-operated bolt mechanismfor such a gun.

Another object of our invention is to provide such a mechanism havingseparate bolt and rammer components.

A further object of our invention is to provide such a bolt componenthaving an inertia member and integral means for locking the component inthe battery position thereof.

A still further object of our invention is to providesuch a gun with arammer for operation responsive to displacement of the bolt.

Other aims and objects of our invention will appear from the followingdiscussion thereof.

In carrying out our invention, the gun is provided with a bolt biased bya spring to a battery position adjacent the breech end of the barrel tochamber a cartridge therein, and the bolt is operable in rearward andforward strokes responsive to discharge of the cartridge to extract thecase of the cartridge from the barrel, subsequent to the discharge. otedon the receiver and connected by a link, is disposed to project acartridge from the feed throat into the barrel, responsive to therearward stroke.

The bolt of our invention is neither required to operate the feeder norto strip cartridges from the ammounition belt. And, since the rammer isa separate component, it may readily be seen that the mass of the boltand the rate of the spring included in the gun of our invention may beconsiderably less than those of the usual gun to increase the rate of reof our gun.

For a more complete understanding of our invention, reference isdirected to the following description and the accompanying drawings inwhich:

Fig. 1 is an elevational view, partly in section, of a machine gunincorporating our invention;

Fig. 2 is a view of one of the lbolt locks in operating position;

A rammer, including a pair of levers fpiv- Fig. 3 is an enlarged viewalong line 3-3 of Fig. l;

Fig. 4 is an enlarged view along line 4 4 of Fig. 3;

Fig. 5 is a view similar to Fig. 4 with the inertia member displacedrearwardly; and

Fig. 6 is a perspective view of the lock member.

Accordingly, a machine gun 12 including a receiver 14 is provided with abarrel 16 and a barrel extension 1S secured thereto. a bifurcatedportion thereof, and a bolt 22 is mounted for sliding movement parallelto the longitudinal axis of barrel 16 by means of a pair oflaterally-opposed rails 24 which are received by cooperating grooves 26in tines 20.

Springs 28 engage -receiver 14 to bias bolt 22 to a battery position forbreech engagement of a surface 30 thereof with the base of a cartridge32 to chamber the carfridge in barrel 16.

Barrel extension 1S includes a piston 34 which is e11- gageable with animpact member 36 sldably disposed in bolt 22 and secured therein by aninsert 3S held in bolt 22 by a pin 40. A spring 42 biases member 36towards a normal position of engagement with insert 33, and an extension43 of member 36 projects from bolt 22 for battery position engagementwith piston 34.

A firing pin 44 is disposed for battery position engagement with theprimer of cartridge 32 and insulated from bolt 22 by a cylinder Li6 ofnonconductive material.r A hook 48 is pivoted on bolt 22 and biased by aspring 49 for engagement with the extraction groove'of cartridge 32.

Bolt 22 includes sides 50 and corresponding lock members 52 are pivotedat 53 in outer recesses 54 of the sides between operating and lockedpositions. Lock members 52 are provided with trunnions 56 which extendoutwardly to be received by cooperating L-slots S8 provided in member36. In the operating position of member 36, trunnions 56 are disposed inbranches 59 of slots 58. Members 52 include extensions 6d disposed tocontinue rails 24 and be slidable in grooves 26 when the members are inthe operating position and thereby slidingly support bolt 22 to permitbolt 22 to slide in barrel extension 18, and to be pivoted out ofalignment with such rails and into engagement with a pair of stops 62 ofbarrel extension 18 when such members are in the locked position tosecure bolt 22 in the battery position thereof.

A cylindrical case 64 including a hanged portion 66 corresponding to ashoulder of member 36 is secured therein by an insulating spacer 68. A`cap 76 is threaded to casing 64. A rod 72 and a ball 74 cupped in cap70 are biased apart by a spring 76 for engagement of a shoulder 78 ofrod 72 with spacer 63 and for engagement of ball 74 with tiring pin 44through a slot Sti in cylinder 46. Rod 72, ball 74 and spring 76 areelectrically insulated from bolt 22.

-Rod 72 extends through spacer 68 for battery position engagement with aspring-biased contact 82 of a terminal 84 electrically insulated frombarrel extension 18 to conduct electric current to the primer ofcartridge 32 for discharge thereof.

Gases from the discharge operate on piston 34 for displacement of member36 rearwardly in bolt 22. Cam surfaces 86 are provided in slots 53 forengagement with trunnions 56 for displacement thereof to branches 88 ofslots 58 and consequent displacement of members 52 to the operatingposition during the rearward displacement. When trunnions S3 arepositioned in Ibranches 88 member 36 engages a surface 9i) to urge bolt$22 in a rearward stroke against springs 28.

The case of discharged vcartridge 32 is carried rearwardly by bolt 22and the case is rotated out of engagement with the bolt responsive toengagement of the base of the case with a stop 92 disposed on receiver14.

Live cartridges 32 are supplied to a substantially cylin- Barrelextension 18 includes tines 20 ofy drical throat 94 by a feeder (notshown) responsive to the discharge, and a rammer 96 includes a pair oflevers 98 and 100 pivoted on receiver 14 with a link 102 connectedtherebetween. Lever 98 is biased free from engagement with a cartridge32 disposed in throat 94 by a spring 104 secured to receiver 14.

The axis of cylindrical throat 94 intersects the axis of barrel 16 atthe breech end thereof, and a cam 106 is provided on bolt 22 forengagement with lever 100, to sequentially project the cartridges fromthroat 94 into barrel 16, responsive to the rearward strokes of bolt 22.

Bolt 22 operates in a forward stroke responsive to spring 28, and as thebolt arrives at the battery position, member 36 is returned toengagement with insert 38 responsive to springs 42, and members 52 pivotto the locked position. Electrical contact between firing pin 44 andcontact 82 is broken as member 36 is displaced rearwardly, and thecontact is completed again when member 36 returns to the normalposition.

Although a particular embodiment of the invention has been described indetail herein, it is evident that many variations may be devised withinthe spirit and scope thereof and the following claims are intended toinclude such variations.

We claim:

l. In a machine gun including a barrel and an extension member mountedon the breech thereof, a bolt device comprising a bolt member actuatablebetween a recoil and a battery position, a bifurcated portion in theextension member to'slidingly receive said bolt member, a pair of tinesformed by said bifurcated portion and disposed for sliding engagementwith the side of said bolt member, a groove extending along the insideof each of said tines parallel to the longitudinal axis of the barrel,supporting means extending from each side of the bolt member for slidingcooperation with said grooves, means for pivotally interrupting saidsupporting means when tracks, means for pivoting said lock members tomove said extension portions out of alignment with said grooves whensaid bolt member is in battery position, and stop portions in theextension member engageable by said extension portions when said lockmembers are pivoted to move said extension portions out of alignmentwith said tracks for blocking said bolt member in battery position.

3. In a machine gun including a barrel, an extension member mounted onthe breech thereof and a piston energized by gases generated in thebarrel during operation of the machine gun, a bolt device comprising abolt member actuatable between a recoil and battery position, abifurcated portion in the extension member for slidingly receiving saidbolt member, a pair of tines formed by said bifurcated portion anddisposed for sliding engagement with the sides of said bolt member, agroove extending along the inside of each of the tines parallel to theaxis of the barrel, an impact member slidingly mounted on said boltmember for movement between a forward and rearward position, said impactmember being disposed for engagement by the energized piston when in theforward position, engaging portions on said bolt and impact member fortransferring the energy from the piston to said bolt member when saidimpact member is in the rearward position, longitudinally-disposed trackportions extending from the sides of said bolt member to be slidinglyreceived by said grooves, recesses formed in each side of said boltmember to interrupt said track porsaid bolt member is in batteryposition to block said bolt t member against rearward displacement, andstop portions in said extension member engageable by said supportingmeans where interrupted for releasably blocking said bolt member in thebattery position.

2. In a machine gun including a barrel and an extension member mountedon the breech thereof, a bolt device comprising a bolt member actuatablebetween a recoil and a battery position, a bifurcated portion formed inthe extension member to slidingly receive said bolt member, a pair oftines formed by said bifurcated portion and disposed for slidingengagement with the sides of said bolt member, a groove extending alongthe inside of each of said tines parallel to the longitudinal axis ofthe barrel, lock members pivotally mounted on opposite sides of saidbolt member, means cooperating with said grooves to slidingly supportsaid bolt member for movement between a battery and recoil positionincluding tracks extending from said bolt member for sliding cooperationwith said grooves and extension portions disposed on said lock membersfor alignment with said tions, a lockmember mounted in each of saidrecesses for pivotal movement between an operating and lock position,extension portions on said lock members disposed to continue said trackswhen said lock members are in the operating position, stop portions in`the extension member engageable by said extension portions when saidlock members are in the lock position to block displacement of said boltmember from battery position, trunnion portions extending from said lockmembers, and slot means in said impact member operationally cooperatingwith said trunnion portions for pivoting said lock members from the lockto the operating position during movement of said impact member from theforward to the rearward position.

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